3 Could not coerce from ‘Map k1 a’ to ‘Map k2 a’
4 because the first type argument of ‘Map’ has role Nominal,
5 but the arguments ‘k1’ and ‘k2’ differ
6 arising from a use of ‘coerce’
7 from the context (Coercible k1 k2)
8 bound by the RULE "map1/coerce" at T10698.hs:13:1-34
9 In the expression: coerce
10 When checking the transformation rule "map1/coerce"